Overall, our study here revealed that MSC intraperitoneal therapy improved DSS-induced colonic inflammation, and the mechanism may be partly by regulating the intestinal Tregs–IgA response, promoting the secretion of IgA in the intestinal lumen, and remodeling the structure and the diversity of the gut microbiota (Figure 7), which provides a potential therapeutic mechanism for HUMSCs in the treatment of IBD. The gene discussed is CD79A; the disease is inflammatory bowel disease.